c# – 如何在不使用剪贴板的情况下复制图像？

我的问题是这部分：

SendMessage(hCaptureWnd,WM_CAP_COPY,0);                    // copy it to the clipboard

它的作用是将图像从窗口复制到剪贴板,然后从中创建一个字节数组.

它可以工作 – 只要你在程序运行时不使用剪贴板.
问题是,这对我自己来说甚至都不起作用,因为我有时复制一些东西,而Visual Studio需要很长时间才能开始调试Web应用程序,然后崩溃.

所以我的问题在这里：
如何在不使用剪贴板的情况下获取图像？
或者更具体地说,如何将hCaptureWnd转换为System.Drawing.Image？

– 编辑：
我错过了说“没有创建文件,我想要一个字节数组”.
它是一个Web应用程序,因此运行应用程序的用户不应具有对文件系统的写访问权限(仅写入临时测试文件)…
– 结束编辑：

/// <summary>
/// Captures a frame from the webcam and returns the byte array associated
/// with the captured image
/// </summary>
/// <param name="connectDelay">number of milliseconds to wait between connect 
/// and capture - necessary for some cameras that take a while to 'warm up'</param>
/// <returns>byte array representing a bitmp or null (if error or no webcam)</returns>
private static byte[] InternalCaptureToByteArray(int connectDelay = 500)
{
    Clipboard.Clear();                                              // clear the clipboard
    int hCaptureWnd = capCreateCaptureWindowA("ccWebCam",// create the hidden capture window
        350,350,0);
    SendMessage(hCaptureWnd,WM_CAP_CONNECT,0);                 // send the connect message to it
    Thread.Sleep(connectDelay);                                     // sleep the specified time
    SendMessage(hCaptureWnd,WM_CAP_GET_FRAME,0);               // capture the frame
    SendMessage(hCaptureWnd,0);                    // copy it to the clipboard
    SendMessage(hCaptureWnd,WM_CAP_DISCONNECT,0);              // disconnect from the camera
    Bitmap bitmap = (Bitmap)Clipboard.GetDataObject().GetData(DataFormats.Bitmap);  // copy into bitmap

    if (bitmap == null)
        return null;

    using (MemoryStream stream = new MemoryStream())
    {
        bitmap.Save(stream,ImageFormat.Bmp);    // get bitmap bytes
        return stream.ToArray();
    } // End Using stream

} // End Function InternalCaptureToByteArray

注(http://msdn.microsoft.com/en-us/library/windows/desktop/dd756879(v=vs.85).aspx)：

HWND VFWAPI capCreateCaptureWindow(
  LPCTSTR lpszWindowName,DWORD dwStyle,int x,int y,int nWidth,int nHeight,HWND hWnd,int nID
);


#define VFWAPI  WINAPI 

typedef HANDLE HWND;
typedef PVOID HANDLE;
typedef void *PVOID;

完整代码供参考

using System;
using System.IO;
using System.Drawing;
using System.Threading;
using System.Windows.Forms;
using System.Drawing.Imaging;
using System.Collections.Generic;
using System.Runtime.InteropServices;


// http://www.creativecodedesign.com/node/66
// http://www.barebonescoder.com/2012/01/finding-your-web-cam-with-c-directshow-net/
// http://www.codeproject.com/Articles/15219/WebCam-Fast-Image-Capture-Service-using-WIA
// http://www.c-sharpcorner.com/uploadfile/yougerthen/integrate-the-web-webcam-functionality-using-C-Sharp-net-and-com-part-viii/
// http://forums.asp.net/t/1410057.aspx


namespace cc.Utility
{


    // bool isCaptured = ccWebCam.CaptureSTA("capture.jpg"); // Access to path C:Program Files (x86)Common FilesMicrosoft SharedDevServer10.0capture.jpg" denied.
    // byte[] captureBytes = ccWebCam.CaptureSTA();

    /// <summary>
    /// Timur Kovalev (http://www.creativecodedesign.com):
    /// This class provides a method of capturing a webcam image via avicap32.dll api.
    /// </summary>    
    public static class ccWebCam
    {
        #region *** PInvoke Stuff - methods to interact with capture window ***

        [DllImport("user32",EntryPoint = "SendMessage")]
        private static extern int SendMessage(int hWnd,uint Msg,int wParam,int lParam);

        [DllImport("avicap32.dll",EntryPoint = "capCreateCaptureWindowA")]
        private static extern int capCreateCaptureWindowA(string lpszWindowName,int dwStyle,int X,int Y,int hwndParent,int nID);  


        private const int WM_CAP_CONNECT = 1034;
        private const int WM_CAP_DISCONNECT = 1035;
        private const int WM_CAP_COPY = 1054;
        private const int WM_CAP_GET_FRAME = 1084;


        #endregion


        private static object objWebCamThreadLock = new object();


        //CaptureToFile(@"D:Stefan.SteigerDocumentsVisual Studio 2010ProjectsPost_Ipagimage3.jpg"):
        public static bool Capture(string filePath,int connectDelay = 500)
        {
            lock (objWebCamThreadLock)
            {
                return cc.Utility.ccWebCam.InternalCaptureAsFileInThread(filePath,connectDelay);
            }
        } // End Treadsafe Function Capture


        public static byte[] Capture(int connectDelay = 500)
        {
            lock (objWebCamThreadLock)
            {
                return InternalCaptureToByteArrayInThread(connectDelay);
            }
        } // End Treadsafe Function Capture


        /// <summary>
        /// Captures a frame from the webcam and returns the byte array associated
        /// with the captured image. The image is also stored in a file
        /// </summary>
        /// <param name="filePath">path the file wher ethe image will be saved</param>
        /// <param name="connectDelay">number of milliseconds to wait between connect 
        /// and capture - necessary for some cameras that take a while to 'warm up'</param>
        /// <returns>true on success,false on failure</returns>
        private static bool InternalCaptureAsFileInThread(string filePath,int connectDelay = 500)
        {
            bool success = false;
            Thread catureThread = new Thread(() =>
            {
                success = InternalCaptureAsFile(filePath,connectDelay);
            });
            catureThread.SetApartmentState(ApartmentState.STA);
            catureThread.Start();
            catureThread.Join();
            return success;
        } // End Function InternalCaptureAsFileInThread


        /// <summary>
        /// Captures a frame from the webcam and returns the byte array associated
        /// with the captured image. The image is also stored in a file
        /// </summary>
        /// <param name="filePath">path the file wher ethe image will be saved</param>
        /// <param name="connectDelay">number of milliseconds to wait between connect 
        /// and capture - necessary for some cameras that take a while to 'warm up'</param>
        /// <returns>true on success,false on failure</returns>
        private static bool InternalCaptureAsFile(string filePath,int connectDelay = 500)
        {
            byte[] capture = ccWebCam.InternalCaptureToByteArray(connectDelay);
            if (capture != null)
            {
                // Access to path C:Program Files (x86)Common FilesMicrosoft SharedDevServer10.0image1.jpg" denied.
                File.WriteAllBytes(filePath,capture);
                return true;
            }
            return false;
        } // End Function InternalCaptureAsFile


        /// <summary>
        /// Captures a frame from the webcam and returns the byte array associated
        /// with the captured image. Runs in a newly-created STA thread which is 
        /// required for this method of capture
        /// </summary>
        /// <param name="connectDelay">number of milliseconds to wait between connect 
        /// and capture - necessary for some cameras that take a while to 'warm up'</param>
        /// <returns>byte array representing a bitmp or null (if error or no webcam)</returns>
        private static byte[] InternalCaptureToByteArrayInThread(int connectDelay = 500)
        {
            byte[] bytes = null;
            Thread catureThread = new Thread(() =>
            {
                bytes = InternalCaptureToByteArray(connectDelay);
            });
            catureThread.SetApartmentState(ApartmentState.STA);
            catureThread.Start();
            catureThread.Join();
            return bytes;
        } // End Function InternalCaptureToByteArrayInThread


        /// <summary>
        /// Captures a frame from the webcam and returns the byte array associated
        /// with the captured image
        /// </summary>
        /// <param name="connectDelay">number of milliseconds to wait between connect 
        /// and capture - necessary for some cameras that take a while to 'warm up'</param>
        /// <returns>byte array representing a bitmp or null (if error or no webcam)</returns>
        private static byte[] InternalCaptureToByteArray(int connectDelay = 500)
        {
            Clipboard.Clear();                                              // clear the clipboard
            int hCaptureWnd = capCreateCaptureWindowA("ccWebCam",// create the hidden capture window
                350,0);
            SendMessage(hCaptureWnd,0);                 // send the connect message to it
            Thread.Sleep(connectDelay);                                     // sleep the specified time
            SendMessage(hCaptureWnd,0);               // capture the frame
            SendMessage(hCaptureWnd,0);                    // copy it to the clipboard
            SendMessage(hCaptureWnd,0);              // disconnect from the camera
            Bitmap bitmap = (Bitmap)Clipboard.GetDataObject().GetData(DataFormats.Bitmap);  // copy into bitmap

            if (bitmap == null)
                return null;

            using (MemoryStream stream = new MemoryStream())
            {
                bitmap.Save(stream,ImageFormat.Bmp);    // get bitmap bytes
                return stream.ToArray();
            } // End Using stream

        } // End Function InternalCaptureToByteArray


    }


}

我试过这样,但它只得到一个黑色的图像……

[DllImport("user32.dll")]
    static extern IntPtr GetWindowDC(IntPtr hWnd);

    [DllImport("gdi32.dll",SetLastError = true)]
    static extern IntPtr CreateCompatibleDC(IntPtr hdc);

    enum TernaryRasterOperations : uint
    {
        /// <summary>dest = source</summary>
        SRCCOPY = 0x00CC0020,/// <summary>dest = source OR dest</summary>
        SRCPAINT = 0x00EE0086,/// <summary>dest = source AND dest</summary>
        SRCAND = 0x008800C6,/// <summary>dest = source XOR dest</summary>
        SRCINVERT = 0x00660046,/// <summary>dest = source AND (NOT dest)</summary>
        SRCERASE = 0x00440328,/// <summary>dest = (NOT source)</summary>
        NOTSRCCOPY = 0x00330008,/// <summary>dest = (NOT src) AND (NOT dest)</summary>
        NOTSRCERASE = 0x001100A6,/// <summary>dest = (source AND pattern)</summary>
        MERGECOPY = 0x00C000CA,/// <summary>dest = (NOT source) OR dest</summary>
        MERGEPAINT = 0x00BB0226,/// <summary>dest = pattern</summary>
        PATCOPY = 0x00F00021,/// <summary>dest = DPSnoo</summary>
        PATPAINT = 0x00FB0A09,/// <summary>dest = pattern XOR dest</summary>
        PATINVERT = 0x005A0049,/// <summary>dest = (NOT dest)</summary>
        DSTINVERT = 0x00550009,/// <summary>dest = BLACK</summary>
        BLACKNESS = 0x00000042,/// <summary>dest = WHITE</summary>
        WHITENESS = 0x00FF0062,/// <summary>
        /// Capture window as seen on screen.  This includes layered windows 
        /// such as WPF windows with AllowsTransparency="true"
        /// </summary>
        CAPTUREBLT = 0x40000000
    }

    [DllImport("gdi32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    static extern bool BitBlt(IntPtr hdc,int nXDest,int nYDest,IntPtr hdcSrc,int nXSrc,int nYSrc,TernaryRasterOperations dwRop);

    [DllImport("gdi32.dll")]
    static extern IntPtr CreateCompatibleBitmap(IntPtr hdc,int nHeight);

    [DllImport("gdi32.dll",ExactSpelling = true,PreserveSig = true,SetLastError = true)]
    static extern IntPtr SelectObject(IntPtr hdc,IntPtr hgdiobj);

    [DllImport("gdi32.dll")]
    static extern bool DeleteDC(IntPtr hdc);

    [DllImport("user32.dll")]
    static extern bool ReleaseDC(IntPtr hWnd,IntPtr hDC);

    [DllImport("gdi32.dll")]
    static extern bool DeleteObject(IntPtr hObject);


    public static void ScreenshotWindow(IntPtr windowHandle)
    {
        Rect Rect = new Rect();

        GetWindowRect(windowHandle,ref Rect);
        int width = Rect.Right - Rect.Left;
        int height = Rect.Bottom - Rect.Top;

        IntPtr windowDeviceContext = GetWindowDC(windowHandle);
        IntPtr destDeviceContext = CreateCompatibleDC(windowDeviceContext);
        IntPtr bitmapHandle = CreateCompatibleBitmap(windowDeviceContext,width,height);
        IntPtr oldObject = SelectObject(destDeviceContext,bitmapHandle);

        BitBlt(destDeviceContext,height,windowDeviceContext,TernaryRasterOperations.CAPTUREBLT | TernaryRasterOperations.SRCCOPY);
        SelectObject(destDeviceContext,oldObject);

        DeleteDC(destDeviceContext);
        ReleaseDC(windowHandle,destDeviceContext);


        Image screenshot = Image.FromHbitmap(bitmapHandle);
        DeleteObject(bitmapHandle);

        screenshot.Save("d:tempmywebcamimage.png",System.Drawing.Imaging.ImageFormat.Png);

        /*
        // TODO - Remove above save when it works
        using (MemoryStream stream = new MemoryStream())
        {
            screenshot.Save(stream,System.Drawing.Imaging.ImageFormat.Png);
            return stream.ToArray();
        }
        */
    }

然后在SendMessage之后(hCaptureWnd,0);

ScreenshotWindow(new IntPtr(hCaptureWnd));